118 



KNOWLEDGE 



[Mav. 1002. 



Some specimenB may, however, be rendered too tran8])arent 

 by the balsam, if so, mount them in a Bhallow cell in some 

 neutral fluid, nucb as camphor water. 



In their ripe condition they may also bo mounted dry as 

 opaque objects. 



Qiii'.KKTT Miciioscoi'M Al, (!i,i'ii. — The list of excursions 

 durins the months from April to October, l',M)2, of the above 

 club, has been sent to me, iind those who may wish to become 

 acquainted with practical collecting of micro specimens would 

 do well to put themselves in communication with the Secretary 

 of the Quekctt Club at 20, Hanover Square, W., with a view to 

 joining the club itself and taking part in these admirably 

 arranged excursions. 



XOTES AND QUERIES. 



E..I.U. — A new work entitled "The Foraminifera . an 

 Introduction to the Study of the Protozoa," by V. Chapman, 

 costing 9s., has just been published and it is likely that this may 

 answer your pui-pose. 



7'. //. A. — The drawing you send is of a h.iir from the larva 

 of Dermestes Beetle and the specimen is the larva itself. These 

 hairs were at one time considered good test objects, and are in 

 fact not to be despised for the purpose. 



Cleric. — The best book for your purpose will be Lewis 

 Wright's " Popular Hand-book to the Microscope," price 2s. 6d. 



C. //. ('. — In addition to the books named in my previous 

 reply, corres)iondents recommend " A Text-book of Plant 

 Diseases caused by Cryptogamic Parasites," by fleorge Massee, 

 of Kew, and Plowright's " Uredineaj and UstilaginesE," Kegan 

 Paul. 



0. T. E. — MocxTiNC. Pollen Grains. — Place these in alcohol 

 and soak for a few days, then transfer to distilled water, then 

 to haematoxylin for about fifteen minutes. Wash again in 

 distilled water, dehydrate in alcohol, clear in .clove oil and 

 mount in Canada balsam. Carmine may be used instead of 

 hajmatoxylin, if preferred. 



.l/i.ss Parish. — Mounting Des.mids.— Preserve in acetate of 

 copper solution, and mount in a shallow cell in the same 

 medium. 



Story, I. E. — A note on the use of the collar correction of 

 objectives will appear in an early number. 



Correspondence is invited on the subject matters dealt with 

 in these columns. Readers may see subjects from different 

 points of view and their criticism will be welcomed. 



Communications and enquiries on Microscopical matters are 

 cordially invited, and shoidd be addressed to M. I. CROSS, 

 Knowledge Office, 326, High Holhorn, W.C. 



NOTES ON COMETS AND METEORS. 



By W. F. Denning, f.r.a.s. 



TiieGubat Southbbn Comet of 1901.— Prof. TheodorBredikhine, 

 of St. Petersburg, has written an interesting paper on the character 

 and changes in the tail of this comet. Tlio paper forms a useful 

 contribution to comelarj physics, and merits close attention from all 

 those interested in the theory of comets. At the Cape Observatory 

 some excellent photographs were taken of the recent comet, and 

 these liave been discussed by Prof. Bredikhine. They give indica- 

 tions that for several hours on April 23rd there occurred a violent 

 eruption of material in an outward direction from the nucleus, and 

 that subsequently to this discharge the nucleus seemed shorn of the 

 usual envelopes." A secondary eruption, of much less prominence 

 than the first, apparently took place on Jime 2nd, but the comet 

 disappeared soon afterwards, and its further developments could not 

 be traced. Prof. Bredikhine considers that the eruptive disturbance 

 of April 23rd set up a rotatory motion in the nucleus in a similar 

 direction to that of the orbital motion. 



ScAECiTT OP Xew Cojiets. — The exceptional rarity of visible 

 comets alluded to in the November number of Knowledge continues. 

 During the whole of the past winter cometary observers have had 

 practically nothing to examine in this field, yet in November, 1892, 

 there were seven comets visible ! Ordinary comet seekers have 

 alighted upon no new objects since Giacobiui at Nice announced his 

 last discovery on 1900, Ueccmber 20, which is sixteen months ago. 

 This absence of comets is remarkable, when we consider the large 

 number of these bodies which were detected during the last quarter 

 of the nineteenth century. It seems highly probable that many of 



these interesting and mysterious objects escape observation owing to 

 the inadequate means l«kea to effect their discovery. It is to be 

 hoped that in following years more observers will engage in this 

 research, for, if it requires close application and no small amount of 

 patience, it is almost certain to be successful in the cnil. 



Lahok Mf.tkoe.~Oii the beauiifully clear evening of March 23nl, 

 at 7h. 25m., a fine meteor, nearly as brilliant as A'enus, was seen by 

 the wriier at Bristol. It passed very slowly through Irsa Major, its 

 lliijht being from 188° + 76° to 190° + 35°, and duration 41 seconds. 

 The nucleus was ]iear-shaped and yellowish ; it left no enduring 

 streak or train, but threw off a few red sparks as it Tolled along. 

 The jirobable radiant <if the meteor was at 11° + 39° near the great 

 nebula in Andromeda and its probable height 71 to 4-5 miles from 

 above Worcester to Thame. It may have belonged to the same 

 stream which furnished a pretty bright meteor on 1887, March 27, 

 at 8h. 47m., and which was seen by Mr. T. W. Biu'khousc at Sunder- 

 land, and bv the writer at Bristol. The radiant was at 1 1° + 35°, and 

 the heights 59 to ."JS miles, velocity 10 miles per second. Another 

 fully recorded observation of the meteor of March 23rd last would be 

 valuable, and enable its real path to be accurately determined. It 

 was an unusually interesting object, and typical of that numerous 

 class of fireballs which appear in the early evening, and are oft<-n 

 directed in long slow flights from radiants at low altitudes in the 

 western region of sky. Later on the same evening (March 2^rd, 

 8h. 50m.) another very conspicuous meteor was noticed at Bristol by 

 some casual observers, jiassing from left to right along the N.K. sky. 

 but it has been impossible to ascertain any further particulars 

 concerning it. 



Bkight Meteors on March 29. — At 8h. IGm. p.m , Mr. J. 

 Halton, of Manchester, observed a meteor rather brighter than 

 Sirius, shooting towards the head of Serpens from between a. and £ 

 Bootis. Mot, on rapid, duration about IJ seconds. At 9h. 45m. another 

 meteor appeared a few degrees imder a Coronae and t, Ilereulis, and 

 travelled along from right to left in a du-ection almost parallel 

 with those stars. 



ButonT Meteoe on April 10. —At 13h. 28m., the writer, at 

 Bristol, observed a meteor brighter than 1st mag. crossing the star 

 a Opliiuehi. It traversed a path of 10 degrees from 2R2i" + 16° to 

 201^° + 6°, and apj)eared to be rather foreshortened and not verv far 

 from its radiant, probably near 265° + 37°, 268° + 48°, or 276° +'69° 

 Colour bluisli-wliitc, motion rather swift. 



THE FACE OF THE SKY FOR MAY. 



By W. Shackleton, f.e.a.b. 



The Sun. — On the 1st the sun rises at 4.35 a.m., and 

 sets at 7.19 p.m. On the 31st he rises at 3.52 a.m., and 

 sets at 8.3 p.m. 



Sunspots are infrequent, but there are indications that 

 the abnormally long period of minimum is drawing to a 

 close and occasional spots mav be looked for. There is a 

 partial eclipse of the sun on the 7th, but wholly invisible 

 in this country though visible in New Zealand and the 

 South Pacific Ocean. 



The Moon: — 



There are only two occultations conveniently observable 

 this month; there is, however, a near approach of the 

 moon to a. Librae ; the following are the particulars : — 



